2 edition of Evaluation of shrinkage-cracking characteristics of structural lightweight concrete found in the catalog.
Evaluation of shrinkage-cracking characteristics of structural lightweight concrete
R G. McKeen
Written in English
|Statement||by R.G. McKeen and W.B. Ledbetter.|
|Contributions||Ledbetter, W B.|
|The Physical Object|
|Number of Pages||20|
Structural lightweight concrete has an in-place density (unit weight) on the order of 90 to lb/ ft3 ( to kg/m3) compared to normalweight concrete with Steel fiber reinforced lightweight-aggregate concrete (SFRLAC) has many advantages applied in structural engineering. In this paper, the autogenous shrinkage and drying shrinkage of SFRLAC for up to days were measured, considering the effects of types of coarse and fine aggregates with the changes of water-to-binder ratio and volume fraction of steel fiber, ://
"Evaluation of Shrinkage-Cracking Characteristics of Structural Lightweight Con crete," by R. G. McKeen and W. B. Ledbetter, Research Report , Texas Trans portation Institute, October "Fired-Clay Aggregates for Use in Flexible Bases," by W. M. Moore, Research Report , Texas Transportation Institute, November ISBN: OCLC Number: Notes: Papers presented during 4 sessions sponsored by ACI Committee , Creep and Shrinkage in Concrete, and ACI Committee , Properties of Concrete at Early Ages, held at the ACI Spring ://
Foamed concrete with porous aggregate can serve as an alternative material for the existing lightweight concrete materials. This building material shows good mechanical and thermal properties, as well as capillary absorption and shrinkage test results that attest the longevity of this building ://?language=en. Evaluation of shrinkage strains To calculate shrinkage stress, shrinkage strains with time should be first estimated. There are several calculation methods to evaluate shrinkage strain: The concrete models published by the Euro-International Concrete Committee (CEB) and by the American Concrete Institute (ACI) have been used widely in ://
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Shrinkage-Cracking Characteristics of Structural Lightweight Concrete Tests were conducted to determine the effect of coarse aggregate type, cement content and curing environment on unrestrained volume changes and restrained shrinkage cracking behavior.
Measurements of restrained shrinkage SHRINKAGE-CRACKING CHARACTERISTICS OF STRUCTURAL LIGHTWEIGHT CONCRETE by W. Ledbetter Associate Research Engineer Texas Transportation Institute and Gisela Nichols Research Assistant Texas Transportation Institute Research Report Synthetic Aggregate Research Research Study sponsored by The Texas Highway Department Shrinkage cracking performance of lightweight concrete (LWC) has been investigated experimentally on ring-type specimens.
LWCs with and without silica fume were produced at water–cementitious material ratios (w/cm) of to with cold-bonded fly minimises concrete cracking. Reducing the volume of aggregate increases the movement in the concrete during shrinking, as the aggregate provides less restraint.
This increases drying shrinkage and consequently the tensile stresses causing concrete cracking. Figure 3: The effects of aggregate volume on concrete shrinkage Drying Shrinkage 1.
Introduction. Concrete is prone to cracking due to the early age volume deformation under restrained conditions. Early-age cracking is actually the result of a complex interaction between various phenomena or properties of concrete , mainly including the autogenous shrinkage, drying shrinkage, thermal deformation, creep, elastic modulus, tensile strength, :// Drying shrinkage is defined as the contracting of a hardened concrete mixture due to the loss of capillary water.
This shrinkage causes an increase in tensile stress, which may lead to cracking, internal warping, and external deflection, before the concrete is subjected to any kind of :// What is concrete shrinkage cracking, how and where does it occur.
Are concrete floor cracks a structural problem. How to recognize and evaluate shrinkage cracks in poured concrete slabs or floors Do shrinkage cracks in poured concrete always need repair.
Questions & answers about cracks in poured or placed concrete slabs: shrinkage crack recognition, diagnosis, evaluation in concrete Drying shrinkage is the contraction in the concrete caused by moisture loss from drying concrete. Shrinkage-compensating concrete is used to minimize cracking and structural movement caused by drying shrinkage in concrete.
The amount of drying shrinkage that occurs in concrete structures depends on the constituent materials, mixture proportions, curing, drying environment, and of concrete?search. CRACKING OF PLASTIC CONCRETE AND DURABILITY PERFORMANCE OF HARDENED CONCRETE.
Eman Ibrahim. mass loss, scaling resistance, settlement cracking, silica fume, shrinkage-compensating admixture, shrinkage-reducing admixture, slag cement, spacing factor.
Evaluation the Air-Void Characteristics and Durability of the Concrete Cracks are categorized as occurring either in plastic concrete or hardened concrete. The causes of each type of cracking depend on many different factors, and may affect appearance only, or they may indicate significant structural distress or a lack of durability.
Cracks may represent the total extent of the damage, or they may point to problems of greater :// in concrete. Non-structural cracking of concrete is a serious problem and the underlying phenomena, namely, shrinkage and creep, need to be better understood.
Mayers SL () Thermal expansion characteristics of hardened cement paste and of concrete. Kaptijn N () Experimental Evaluation of Autogenous Shrinkage of Lightweight Aggregate Concrete R Guide for the Use of Shrinkage-Compensating Concrete; R Reapproved Control of Cracking in Concrete Structures; R Causes, Evaluation, and Repair of Cracks in Concrete Structures; R Reapproved Cracking of Concrete Members in Direct Tension; R Reapproved Joints in Concrete Construction Concrete pavements subjected to fast evaporation during the first hours after concrete placing are prone to plastic shrinkage cracking.
In this paper the mechanisms by which evaporation of water Non Structural Cracks Non-structural cracks are not of so much significance as far as safety is considered but it deals more with aesthetic point of view. REASONSOF CRACKING A. CRACKING WHICH OCCUR IN PLASTIC CONCRETE 1.
PLASTIC SHRINKAGE CRACKING It arise when the rate of evaporation of water from top layer of freshly laid concrete is The investigation involved the evaluation of the benefits of using saturated lightweight sand (LWS) for internal curing, for expansive agent (EA) shrinkage compensation, and fibers to reduce shrinkage and enhance and corrosion strength resistance of reinforcing bars of structural concrete that can be used in bridge construction and A concrete mixture with w/b of based on Portland cement blended with fly ash and silica fume was examined (see Table 1).The oxide compositions of the general-purpose Portland cement (GP cement), fly ash, and silica fume can be found in Table particle size distributions of the sands and the aggregate used in the concrete mixture are listed in Table :// Aslam et al.
(c) investigated the drying shrinkage behaviour of structural lightweight aggregate concrete using blended oil palm bio-products. They reported that 7-day moist cured concretes Restrained Shrinkage Cracking. Concrete is expected to crack whenever the tensile stress induced by the constraint for the free shrinkage surpasses its tensile strength.
The crack developments and the shrinkage cracking age of the restrained shrinkage specimens are shown in Figure 15 while the maximum crack width of SCCs is given in Table :// However, the introduction of lightweight aggregate (LWA) will lead to reduction of cracking, tensile, and flexural strength even with less negative impact on compressive strength.
Adding steel fiber into the high-strength concrete can significantly improve fracture performance of the concrete (ASCE)MT Very high ultimate autogenous shrinkage of ultra-high-performance fiberreinforced concrete (UHPFRC) is normally obtained due to the use of low water-tobind ?genre.
The early age volume deformation is the main course for the cracking of high-performance concrete (HPC). Hence, the shrinkage behavior and the restrained stress development of HPC under different restraints and curing conditions were experimentally studied in this paper.
The method to separate the stress components in the total restraint stress was ://Shrinkage characterized by the free strain, for normal-strength concrete at 28 days approximately -2 ×attributable to the restraining action of reinforcement causes tension in the concrete and may significantly affect the cracking resistance and deformations of RC members.
In spite of this, the constitutive laws were derived by using (ASCE)STX —Curing special concrete —Length of curing —Preventing plastic-shrinkage cracking —Curing after grinding —Protection of slab during construction —Temperature drawdown in cold storage and freezer rooms —Joint filling and sealing Chapter 10—Quality control checklist, p.
R — R Guide for Concrete Floor and Slab Construction.